A number of different types of apparatus and methods have been employed for bending panels.
U.S. Pat. Nos. 4,347,726 and 4,603,572 disclose apparatus and methods for this purpose. In the past when channel-shaped panels have been formed, the creases formed in the material go in from the base or bottom wall and out from the side. Some of the bending apparatus heretofore provided is for bending a flat plate and others are directed to bending channel-shaped panels.
EPC No. 0,049,313 discloses a panel bending apparatus using a multi-part die and a variable adjustable pressing force.
Sweden No. 459,481 discloses a method and apparatus for bending corrugated sheet using a flat bottom die and a movable top die that has the effect of crushing the corrugations but the movable die does not go past the plane of the panel. Subsequent bending is done manually.